So what they do is, they're describing how these thermodynamic properties change, in terms of only state functions and state variables.

他们的作用是描述,随着状态函数和状态变量的变化，系统的热力性质如何变化。

麻省理工公开课 - 热力学与动力学课程节选

So now, this equation here relates three state functions together: the pressure the volume, and the temperature. Now, if you remember, we said that if you had a substance, if you knew the number of moles and two properties, you knew everything about the gas.

压强，体积和温度,大家应该还记得,我们提过，只要知道气体的摩尔数,和任意两个状态函数,就可以推导出其他的状态函数，这样，我们可以把它改写成。

麻省理工公开课 - 热力学与动力学课程节选